Accelerated, Pulsed Collagen Cross-Linking versus the Dresden Protocol in Keratoconus: A Case Series

Purpose: The aim of our study was to compare the depth of the demarcation line developing in the cornea after the standard Dresden protocol versus the accelerated, pulsed, epithelium-off corneal collagen cross-linking (CXL). Methods: This was a nonrandomized, retrospective case series. Patients with progressive keratoconus were treated with either the standard Dresden protocol (Group 1) or accelerated, epithelium-off CXL using the Avedro (Waltham, MA, USA) device (Group 2). The accelerated CXL protocol involved 18 min of pulsed ultraviolet-A (20 mW/cm², 7.2 J/cm², pulsed pro-file: 1 s on, 2 s off). The depth of the demarcation line was measured about 3 months postoperatively. Results: Fifty-nine eyes of 35 subjects were included in the analysis. Group 1 consisted of 19 eyes, and Group 2 of 40 eyes. The mean age of the participants was 22.21 years in Group 1 and 26.55 years in Group 2 ( p = 0.184). The mean preoperative K value was 44.89 D in Group 1 and 45.20 D in Group 2 ( p = 0.768). The depth of the demarcation line was 322.50 μm in Group 1 and 319.95 μm in Group 2 ( p = 0.937). Conclusions: The demarcation line depth was not statistically significantly different between the two protocols. The significance of the demarcation line depth has not been fully clarified in the literature. Our results support the contention that these two techniques may have similar structural outcomes and efficacies in the treatment of keratoconus.